High-density electrofuels (e-fuels) produced with the help of electricity from renewable energy sources, water and CO2 from the air are crucial to decarbonising long-haul transport. Mildly oxygenated compounds could help overcome the limitations of known e-fuels (such as non-oxygenated Fischer-Tropsch hydrocarbons or heavily oxygenated methanol), but there is not an efficient route for their production. The EU-funded E-TANDEM project will develop a hybrid process to convert CO2, water and renewable energy to higher oxygenate e-fuels that integrates three types of catalysis.
Carbon neutral, high-energy density e-fuels are crucial to de-fossilize long-haul transport. Mildly oxygenated compounds such as C5+ (higher) alcohols and their ether derivatives hold the promise to overcome limitations of known e-fuels, such as non-oxygenated Fischer-Tropsch hydrocarbons or heavily oxygenated methanol and DME, but no process exists for their effective production.
The project aims to develop a disruptive route wherein CO2, water and renewable power are converted to higher oxygenate e-fuels in a once-through hybrid process integrating three major catalysis branches: “electrocatalysis” is applied in a robust high-pressure CO2/H2O co-electrolysis step to produce e-syngas (H2/CO), which is converted in a single-reactor, slurry-phase process combining “solid thermocatalysis” for linear hydrocarbon synthesis and “molecular chemocatalysis” for in situ oxo-functionalization via reductive hydroformylation. In this process, integration of catalytic functionalities in tandem, alongside an engineered interfacing of high- and low-temperature conversion steps and energy unintensive membrane separation technologies, offer a blueprint for superior atom and energy efficiencies.
The project will demonstrate the new e-fuel production process at bench-scale, and assess its capacity to cope with fluctuating energy inputs. Moreover, e-fuel formulation and life-cycle aspects are covered to fully realize the potential of the higher oxygenate e-fuel to distinctively unite excellent combustion properties (high cetane), exceptional reduction of tailpipe soot emissions, advantageous logistics as liquid at ambient conditions and compatibility with current-fleet fuel infrastructure and engine technologies, with emphasis on applications as diesel replacement in heavy-duty marine transport. An exploitation plan will be created together with international stakeholders, to consolidate EU’s capacity to export advanced e-fuel technologies to areas with vast green energy potential.